Permittivity properties of thermally treated TiO_2

摘要

Pure titanium oxide (TiO_2) is an environmentally stable material, having interesting dielectric properties that can be practically utilized for microwave applications, and biological tissue simulations. In this study, the permittivity-frequency response of compressed TiO_2 being calcined under different conditions, were investigated for the frequency range 20 Hz-1 MHz, as well as the microwave frequency regime 2.6-3.2 MHz. The calcination effect on the microcrystal structure has been studied by XRD, SEM and microhardness. The acquired complex permittivity values are correlated to the encountered structural changes: The anatase microcrystal structure (maintained for calcination temperatures below 915 deg C) exhibits significant ionic-relaxation and value-variations in the low frequency regime. The rutile microcrystal structure almost attains relaxation free permittivity response, with low loss characteristics in the examined frequency range. Calcination temperature of 1180 deg C provides ceramics with a high packing microcrystal density, having stable epsilon_r' = 12.3 and tan(delta) 2.3 X 10~(-3) (at 1 MHz).